1. Field
Embodiments of the present invention relate to a solenoid valve for a brake system to assure easier manufacture and lower manufacturing costs than the related art.
2. Description of the Related Art
A general vehicular anti-lock brake system is designed to prevent wheel lockup when braking hard by controlling braking pressure applied to wheels based on sensed tire slip.
This assures directional stability and steering control of wheels without tire slip during braking and consequently, safe braking.
This type of brake system includes a plurality of solenoid valves that opens or closes flow-paths of brake hydraulic lines to control braking pressure. Solenoid valves may be classified into normally opened type solenoid valves that are normally kept in an opened state, and normally closed type solenoid valves that are normally kept in a closed state.
FIG. 1 is a sectional view illustrating a conventional normally opened type solenoid valve for a brake system.
Referring to FIG. 1, the conventional normally opened type solenoid valve (hereinafter, referred to as a solenoid valve) is installed in a modulator block 1 for enhanced integration. For installation of the valve, a valve bore 2 is cut in the modulator block 1.
The valve bore 2 is connected to an inner flow-path formed in the modulator block 1, and a magnet core 3 is inserted into the valve bore 2.
A cylindrical sleeve 5 is coupled to one end of the magnet core 3 and in turn, an armature 4 is movably received in an interior hollow of the cylindrical sleeve 5. A plunger 7 is integrally formed at one end of the armature 4, to allow the armature 4 to open or close an orifice 6a of a valve seat 6 via movement thereof. An elastic member 9 is interposed between the plunger 7 and the valve seat 6.
A lower portion of the magnet core 3, in which the valve seat 6 is axially received, is inserted in the bore 2 with a predetermined clearance from an inner periphery of the bore 2. A lip seal 8 is fitted around the lower portion of the magnet core 3. The lip seal 8 is made of elastic material and functions as a check valve.
The lip seal 8 takes the form of a loop that is provided at an edge thereof with an elastic piece. To install the lip seal 8, an annular seating recess 3a is formed in an outer periphery of the magnet core 3 near a lower end thereof. If braking pressure is applied to the lip seal 8, the elastic piece of the lip seal 8 spreads out in a radial direction, thus coming into close contact with the inner periphery of the bore. Thereby, the braking pressure is transmitted to a brake through the orifice 6a and an outlet 10 of the modulator block. On the other hand, the elastic piece is retracted toward the center by hydraulic pressure upon release of the braking pressure, thus being spaced apart from the inner periphery of the bore 2 to create a pressure-release flow-path. This may cause the braking pressure to be partially transmitted to a master cylinder through an inlet.
However, in the above-described conventional solenoid valve for a brake system, the plunger and valve seat are mounted in the magnet core and also, the lip seal is mounted around the magnet core. Therefore, inserting the magnet core into the bore may require an excessively long length and complex configuration of the magnet core, resulting in higher production price.
Further, the sleeve is press-fitted around an upper portion of the magnet core and is fixed thereto by welding. This fixing configuration however may increase assembly costs.
Furthermore, when the armature opens or closes the orifice of the valve seat by movement of the plunger, reduction of manufacturing costs is limited.